The elephant-like Mammomax was recruited into a new Brotherhood Of Mutants led by Exodus who first clashed with the X-Men in Philadelphia. The villains were quickly dispatched, with Mammomax being easily incapacitated by Iceman. Escaping, the Brotherhood subsequently attacked the Xavier Institute. Mammomax was severely beaten by the Juggernaut before the villains were pulled into an apparent black hole created by the pacifist Xorn. Following the advent of "M-Day," Mammomax was one of the 198 mutants to have retained their abilities. Mammomax along with Erg and Peepers fled to the Institute seeking sanctuary from persecution by Sapien League terrorists. They were saved from crucifiction by Wolverine and Colossus, and has since taken up residence in the tent city established on the school's grounds.
Recently, it was revealed that Mammomax was killed during experiments to create a weapon against mutants. His remains were witnessed by the New X-Men, Mercury (Cessily Kincaid) while she was captured during the same experiment.